1. Field of the Invention
The present invention relates to an image composition apparatus, an image retrieval method, and a storage medium storing program.
2. Description of the Related Art
For example, as disclosed in Jpn. Pat. Appln. KOKAI Pub. No. 2004-134950 (hereinafter referred to as Patent Document 1), a conventional technique of executing image composition by superposing a material image on an image taken by a digital camera or the like has been well known in the prior art.
In addition, as disclosed in Jpn. Pat. Appln. 11-341522 (hereinafter referred to as Patent Document 2), known is a technique of preparing a pair of left and right images, which have parallax between them, that is, a left-eye image and a right-eye image in which the position of the same object in the image is shifted to the left and the right, causing the user to view the left-eye image by the left eye and view the right-eye image by the right eye, and thereby causing the user to view the image in a three-dimensional manner (as a three-dimensional image).
In the meantime, the left-eye image and the right-eye image which form an image (hereinafter referred to as “three-dimensional image”) which is viewed in a three-dimensional manner by the technique disclosed in Patent Document 2 are still images which are similar to images taken by a digital camera or the like. Therefore, it is possible to extract a partial image (hereinafter referred to as “object image”) which corresponds to a part (hereinafter referred to as “object”) that is recognized as an independent object such as a person from a three-dimensional image, and superpose the extracted partial image on another three-dimensional image. Specifically, a left-eye image of an object image is superposed on a left-eye image which forms a three-dimensional image forming a background, a right-eye image of the object image is superposed on a right-eye image which forms the three-dimensional image forming the background, and thereby a new three-dimensional image can be formed.
However, in the case where a three-dimensional image includes a plurality of objects which are viewed in a three-dimensional manner as having different distances, when part of an object which is perceived as relatively existing in the front is hidden by another object which is perceived as relatively existing in the rear, the three-dimensional image produces a very unnatural impression. Therefore, when a desired object image is superposed on any of a plurality of prepared three-dimensional images, it is necessary to select a three-dimensional image for a background, which is suitable for image composition, in consideration of a difference in distance from other objects in a composed three-dimensional image.
Therefore, when a background three-dimensional image is selected, it is necessary for the operator to check in advance whether or not a composed three-dimensional image produces an unnatural impression, by viewing the object image together with each three-dimensional image which can be selected as a background in a three-dimensional manner. This requires much labor for selecting a background three-dimensional image, and causes the problem of increase in the load on the operator.